Fuel supply apparatus using low boiling point fuel and its control method

ABSTRACT

A fuel supply apparatus reduces the fuel vaporization and leakage by means that the positions of vaporization and leakage and their amount in the fuel tank and the fuel pipe is detected properly in case of using a low boiling point fuel having a vapor phase in the normal temperatures and atmospheric pressures, and the fuel state is controlled based on those detected values. By providing another container made of elastomatic material having an expandable mechanical characteristic inside the fuel storing container, the low boiling point fuel is stored in the separate container. A flow rate controlling apparatus is provided for heating or cooling the fuel pipe leading the low boiling point fuel stored in the fuel storing container to the engine. A flow rate controlling apparatus is provided for adjusting the flow rate of the fuel in the fuel pipe for leading the low boiling point fuel stored in the fuel storing container to the engine. An adjusting apparatus is provided for at least one of the fuel pressure and the fuel temperature in responsive to the output signal from the control apparatus generating the electric signal in responsive to at least one of the fuel leakage volume and the fuel vaporization state.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a fuel supply apparatus for lowboiling point fuel vaporized at normal temperatures and underatmospheric pressures, and specifically to preventing vaporization andleakage of the fuel.

[0002] From the point of view regarding to the terrestrial environmentproblems typified by global warming and the energy problems, low carbonfuels such as natural gas (CNG, LNG), liquefied petroleum gas (LPG) anddimethyl ether (DME) are being introduced for the engines such asautomobile internal combustion engine. As the number of carbon atoms inthe individual fuel molecule is less than that of the gasoline and thepetroleum, and their heat release value per a single carbon atom ishigher than that of the gasoline and the petroleum, the umber of carbonatoms for an identical heat release value becomes reduced in thosefuels. This means that the amount of emitted gaseous CO2 from the enginecan be reduced, which leads advantageously to preventing the globalwarming and to the energy saving. An application of DME is proved to bevalid for an alternative fuel for the diesel engines because it isproved that there is no soot generated. As those low carbon fuels havelow boiling point and stay in a gaseous phase at normal temperatures andunder an atmospheric pressure. For example, in case of applying thosefuels into diesel engines, it is required to maintain its liquid phaseby pressurizing or cooling the fuel properly and to inject the fuel intothe combustion chamber by using a high pressure pump. In this operation,there are such problems as defect in the fuel feed operation and fuelleakage outside the fuel supply system due to the fuel vaporization inthe fuel pipe extended from the fuel tank because the fuel has a lowboiling point. As for the technologies solving those problems, theredisclosed a technology found in Japanese Patent Laid-Open Number2001-115916 in which the feed pressure in the feed pump installed in thefuel tank is controlled in responsive to the map prepared based on theDME vapor pressure chart and the detected value of the fuel pressure.

[0003] There still remain such problems in the prior art as describedbelow.

[0004] As the vapor pressure chart of the fuel is determined uniquely bythe fuel temperature, the feed pressure of the fuel pump is dominated bythe fuel temperature at the sensing point of the temperature sensor.This means that this technology can not solve the fuel vaporization orleakage in case that there exists a local heat spot in the fuel pipe.

SUMMARY OF THE INVENTION

[0005] On this subject, an object of the present invention is to providea fuel supply apparatus and its control method enabling to reduce orprevent the fuel vaporization and leakage by means that the fuel statein the fuel tank and the fuel pipe (for example, the positions ofvaporization and leakage and their amount) is detected properly in caseof using low boiling point fuels having a vapor phase in the normaltemperatures and atmospheric pressures, and the fuel state is controlledbased on those detected values.

[0006] In order to attain the above object, in the present invention, anadditional elasticated container made of elastomeric material isinstalled inside the fuel storing container, and the low boiling pointfuel is stored in this additional container.

[0007] In another invention, a temperature control apparatus is providedfor heating or cooling the fuel pipe supplying the low boiling pointfuel stored in the fuel storing container to the engine.

[0008] In another invention, a flow rate control apparatus is providedfor regulating the fuel flow in the fuel pipe supplying the low boilingpoint fuel stored in the fuel storing container to the engine.

[0009] In another invention, a adjusting apparatus is provided forregulating at least either of the fuel pressure or the fuel temperaturein responsive to the output signal from the control apparatus generatingan electric signal in responsive to at least either of the fuel leakagevolume or the fuel vaporization state.

[0010] In another invention, a fuel flow rate adjusting apparatus isprovided for adjusting the flow rate of fuel in the fuel pipe only whenthe relation between the fuel pressure inside the fuel pipe supplyingthe fuel from the fuel storing container to the engine and the fueltemperature in side the fuel pipe supplying the fuel from the fuelstoring container to the engine reaches a specified condition.

BRIEF DESCRIPTION OF DRAWINGS

[0011]FIG. 1 is a structure of the fuel supply apparatus and its controldiagram in the first embodiment of the present invention.

[0012]FIG. 2 is a flowchart for controlling the fuel state in theoperation of the engine in the first embodiment of the presentinvention.

[0013]FIG. 3 is a relationship between the target feed pressure valueand the output value from the fuel pressure sensor in the firstembodiment of the present invention.

[0014]FIG. 4 is a relationship between the target feed pressure valueand the output value from the fuel pressure sensor in the start-upoperation of the engine in the first embodiment of the presentinvention.

[0015]FIG. 5 is a flowchart for controlling the start-up operation inthe first embodiment of the present invention.

[0016]FIGS. 6A, 6B and 6C are configuration examples of the coolingstructure of the fuel pipe and the temperature adjusting device in thefuel supply apparatus of the present invention.

[0017]FIG. 7 is a structure of the fuel supply apparatus and its controldiagram in the second embodiment of the present invention.

[0018]FIG. 8 is a flowchart for controlling the fuel state in theoperation of the engine in the second embodiment of the presentinvention.

[0019]FIG. 9 is a relationship between the target feed pressure valueand the output value from the fuel pressure sensor in the secondembodiment of the present invention.

[0020]FIG. 10 is a relationship between the target feed pressure valueand the output value from the fuel pressure sensor in the start-upoperation of the engine in the second embodiment of the presentinvention.

[0021]FIG. 11 is a flowchart for controlling the start-up operation inthe second embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The basic configuration of the embodiment for implementing thepresent invention is described as below.

[0023] In the fuel supply apparatus for supplying the low boiling pointfuel having a vapor phase at the normal temperatures and the atmosphericpressures, what are provided are a fuel storing means for storing thelow boiling point fuel; a fuel conveying means for conveying the lowboiling point fuel from the fuel storing means; a fuel pipe for leadingthe low boiling point fuel to be conveyed from the fuel storing means; afuel leakage protecting means for preventing the leakage of the lowboiling point fuel in the fuel storing means or in the fuel pipe; a fuelleakage detecting means for detecting the fuel leakage in the fuelstoring means or in the fuel pipe; a fuel state detecting means fordetecting the fuel state in the fuel storing means or in the fuel pipe;and a fuel state controlling means for controlling the fuel state in thefuel storing means or in the fuel pipe, in which at least one of thestates in the fuel storing means, the fuel conveying means, the fuelpipe and the fuel leakage protecting means is controlled by the fuelstate controlling means in responsive to the detection result by thefuel state detecting means and said fuel leakage detecting means.

[0024] More specifically and preferably, in the above described fuelsupply apparatus, the fuel state controlling means controls at least oneof the temperature, the pressure and the shape in the fuel storingmeans, the fuel pipe and the fuel leakage protecting means in responsiveto the detection result by the fuel state detecting means and the fuelleakage detecting means.

[0025] In addition, the following configurations are preferablyprovided.

[0026] In the fuel supplying apparatus, the above described fuel statecontrolling means preferably controls the voltage of the fuel conveyingmeans in responsive to the detection result by the fuel state detectingmeans and the fuel leakage detecting means.

[0027] In the above described fuel supplying apparatus, the fuel leakageprotecting means is preferably provided inside the fuel storing means,and the fuel leakage protecting means is made of elastomatic materialhaving an expandable mechanical characteristic and stores the lowboiling point fuel inside this elasticated container.

[0028] The above described fuel leakage protecting means adjustspreferably the internal volume of the elasticated container inresponsive to the detection result by the fuel state detecting means andthe fuel leakage detecting means.

[0029] The above described fuel supplying apparatus preferably has afuel state controlling means outside the fuel pipe.

[0030] The fuel state controlling means preferably has a adjustingdevice attached to the fuel pipe.

[0031] The fuel state controlling means is defined as refrigerationmedium passing through the pipe attached to the fuel pipe and itstemperature is controlled by the temperature-adjusting device.

[0032] The refrigeration medium is preferably water, which passesthrough the pipe attached to the fuel pipe into the radiator for thecooling water.

[0033] The fuel leakage detecting means is preferably composed of atleast one of a fuel pressure sensor provided in the fuel pipe, apressure sensor provided in the fuel storing means, a fuel temperaturesensor provided at the fuel pipe or the fuel storing means, a fuelremaining sensor for detecting the remaining low boiling point furl inthe fuel storing means, a volume detecting sensor for detecting thevolume of the elasticated container provided in the fuel storing meansand a fuel conveying means, and estimates the fuel leakage amountaccording to the output signals from the individual sensors and meansand their calculation result.

[0034] The fuel leakage detecting means is preferably composed of atleas one of a fuel pressure sensor provided in the fuel pipe, a pressuresensor provided in the fuel storing means, a fuel temperature sensorprovided at the fuel pipe or the fuel storing means, a fuel remainingsensor for detecting the remaining low boiling point furl in the fuelstoring means, a volume detecting sensor for detecting the volume of theelasticated container provided in the fuel storing means and a fuelconveying means, and estimates the fuel leakage location according tothe output signals from the individual sensors and means and theircalculation result.

[0035] The operation of the internal combustion engine is preferablyterminated in case that the estimated value for the fuel leakage amountis a designated value or larger.

[0036] The fuel leakage alarming means is preferably provided forsignaling at least one of the alarm sound or the alarm lamp in case thatthe estimated value for the fuel leakage amount is a designated value orlarger.

[0037] The fuel leakage location alarming means is preferably providedfor reporting the estimated result for the fuel leakage location.

[0038] Preferably, in case that at least one means of the fuel storingmeans for storing the low boiling point fuel; the fuel conveying meansfor conveying the low boiling point fuel from the fuel storing means tothe engine; the fuel pipe for leading the low boiling point fuel to beconveyed from the fuel storing means to the internal combustion engine;the fuel leakage protecting means for preventing the leakage of the lowboiling point fuel in the fuel storing means or in the fuel pipe; thefuel leakage detecting means for detecting the fuel leakage in the fuelstoring means or in the fuel pipe; the fuel state detecting means fordetecting the fuel state in the fuel storing means or in the fuel pipe;and the fuel state controlling means for controlling the fuel state inthe fuel storing means or in the fuel pipe is defected, the operation ofthe internal combustion engine is terminated.

[0039] Preferably, in case that at least one means of the fuel storingmeans for storing the low boiling point fuel; the fuel conveying meansfor conveying the low boiling point fuel from the fuel storing means tothe engine; the fuel pipe for leading the low boiling point fuel to beconveyed from the fuel storing means to the internal combustion engine;the fuel leakage protecting means for preventing the leakage of the lowboiling point fuel in the fuel storing means or in the fuel pipe; thefuel leakage detecting means for detecting the fuel leakage in the fuelstoring means or in the fuel pipe; the fuel state detecting means fordetecting the fuel state in the fuel storing means or in the fuel pipe;and the fuel state controlling means for controlling the fuel state inthe fuel storing means or in the fuel pipe is defected, the fuel leakagealarming means is provided for signaling at least one of the alarm soundor the alarm lamp.

[0040] Preferably, in case that at least one means of the fuel storingmeans for storing the low boiling point fuel; the fuel conveying meansfor conveying the low boiling point fuel from the fuel storing means tothe internal combustion engine; the fuel pipe for leading the lowboiling point fuel to be conveyed from the fuel storing means to theinternal combustion engine; the fuel leakage protecting means forpreventing the leakage of the low boiling point fuel in the fuel storingmeans or in the fuel pipe; the fuel leakage detecting means fordetecting the fuel leakage in the fuel storing means or in the fuelpipe; the fuel state detecting means for detecting the fuel state in thefuel storing means or in the fuel pipe; and the fuel state controllingmeans for controlling the fuel state in the fuel storing means or in thefuel pipe is defected, the fuel system fault location alarming means isprovided for reporting which means is fault.

[0041] Now, by referring to the figures, the embodiment of the presentinvention is described in detail.

[0042]FIG. 1 illustrates the configuration of the fuel supplyingapparatus and its control flow diagram schematically in the firstembodiment of the present invention. The configuration of thisembodiment is characterized by that the fuel feed pump 6 is used as thefuel conveying means and that the temperature of the fuel pipe 15 can becontrolled by the heat insulating material 16 and the temperatureadjusting device 12. The component 3 in FIG. 1 is a fuel tank used asthe means for storing the fuel 5. The fuel 5 is a low boiling point fuelhaving a gaseous phase state in the normal temperatures and under theatmospheric pressures, for example, LNG (Liquefied Natural Gas), LPG(Liquefied Petroleum Gas) and DME (Dimethyl Ether).There is anelastometic film 4 inside the fuel tank 3. This elastomatic film 4 ofthe container has such a material characteristic having an expandablemechanical characteristic, which enables to protect the leakage from thefuel tank 3 because the inside pressure of the tank can be buffered withthe elastomatic characteristic of the elastomatic film 4 by means ofstoring the low boiling point fuel 5 inside the film even if the volumeof the low boiling point fuel increases and its inside pressureincreases when the low boiling point fuel 5 evaporates. In addition, thefuel tank 3 has the fuel supply port 2, the feed pump 6 for conveyingthe fuel, the fuel remaining volume sensor 7 for detecting the fuelremaining volume, the pressure sensor 8 for detecting the pressure Iside the fuel tank 3, ad the sensor 10 for detecting the expansion andcontraction of the elastomatic film 4. The sensor 10 is preferablyformed as a distortion sensor, which can detects the expansion andcontraction of the elastomatic film 4 in responsive to the changes inthe electric resistance in the sensor 10 due to the expansion andcontraction of the elastomatic film 4. The component 22 is a magneticvalve, which controls the fuel flow rate between the fuel tank 3 and thefuel pipe 15 by using the magnetic valve controller 11 and can breakdown the fuel flow between them when the fuel leakage occurs or the fuelsupply fails. The control method of those components will be describedlater. The component 16 is a heat insulating material, which protectsthe fuel pipe 15 from the heat generated outside and prevents the fuelin the fuel pipe 15 from being vaporized. In case that the fuel pipe 15is formed preliminary as a heat-insulated member, the heat insulatingmaterial 16 is not required. The component 12 is a temperature adjustingdevice for controlling the temperature of the fuel pipe 15. Thecomponent 13 is a fuel pressure sensor and the component 14 is a fueltemperature sensor, which detect the fuel pressure and temperature ofthe fuel flowing in the fuel pipe 15. The locations of the fuel pressuresensor 13 and the fuel temperature sensor 14 are not definedspecifically but it may be preferable that the fuel pressure sensor 13and the fuel temperature sensor 14 are located relatively in a shortdistance to each other. The component 19 is an engine, which ispreferably configured as an internal combustion engine in which the pump17 is provided and the fuel with its pressure increased by the pump 17is directly injected into the combustion chamber 18 through the injector20. As this embodiment is characterized as the fuel supplying apparatusfor conveying the low boiling point fuel 5 from the fuel tank 3 to theengine 19, the operation mode (whether it is implemented as the internalcombustion engine, the external combustion engine or the fuel cell) orthe configuration (whether the pump 17 is used or not) of the engine isnot defined specifically. Assuming that the engine 19 is an internalcombustion engine, this embodiment is further described below. Thecomponent 1 is an engine control unit (hereinafter referred to as ECU)for controlling the operation status of the engine 19. In thisembodiment, in the fuel tank 3 and the fuel pipe 15, the fuel state(whether it is in a vapor phase or in a liquid phase), the fuel leakagevolume and the fuel leakage location are detected or estimated from thevalues obtained by the above described sensors, and the instructions forcontrolling the fuel state are calculated and determined. Based on thosecomputational results, by using the feed pump 6, the magnetic valvecontroller 11 and the temperature adjusting device 12, the fuel state inthe fuel tank 3 and the fuel pipe 15 is controlled. The method forcontrolling the fuel state in this embodiment is described below byreferring to FIGS. 2 to 6.

[0043]FIG. 2 shows an flow chart for controlling the fuel state in thefirst embodiment of the present invention in which the engine 19 (aninternal combustion engine in this embodiment) is in operation. In FIG.2, when the engine 19 is in operation, the fuel 5 is fed by the feedpump 6 with a designated pressure (Block 1001). This feed pressure isselected from the target feed pressure values predefined in ECUL inresponsive to the operational condition, the ambient air condition andthe output value from the fuel temperature sensor 14. Next, the fuelpressure and temperature in the fuel pipe 15 are detected by the fuelpressure sensor 13 and the fuel temperature sensor 14, and the outputvalues from the fuel remaining volume sensor 7, the pressure sensor 8the elastomatic film expansion sensor 10 are read in as the informationon the state inside the fuel tank 4 (Block 1002). At this step, bycomparing the target feed pressure value with the output value from thefuel pressure sensor in the fuel pipe 15, the feed back control isperformed so that the output value from the feed pump may become thetarget feed pressure value. Next, the fuel state is judged (Block 1003),and then the target feed pressure is increased when the vaporized fuelexists (Block 1004). In case that there exists a vaporized fuel yetafter increasing the target feed pressure, the fuel pipe 15 is madecooled by operating the temperature adjusting device 12 (Block 1005). Incase that the fuel leakage is detected in the result of Block 1003, thepressure of the feed pump is decreased (Block 1006), and in case thatthe engine 19 is loaded in the vehicle, the fixed power generator or thefixed compression refrigerating machine, the warning sound or light isissued to the user of the vehicle (Block 1007). In case that the fuelleakage volume is large or that the fuel leakage volume is a given valueor larger even after decreasing the feed pump pressure, the operation ofthe engine is terminated by shutting down the fuel supply by closing theelectromagnetic valve 22 after issuing the warning signal to the user(Block 1008). In case that the engine 19 is used in a vehicle and itssystem is configured like a hybrid automotive in which the drive systemis driven by the motor as well as the engine 19, it is allowed tooperate the drive system with the motor while the fuel supply to theengine 19 is suspended. As for the fuel state in the fuel tank 3, thegaseous phase volume and the liquid phase volume in the fuel tank 3 isestimated by the output value, read in at Block 1002, from the fuelremaining volume sensor 7 and the elastomatic film expansion sensor 10(Block 1009), and the target pressure value Pft in the fuel tank 3 iscalculated (Block 1010). Comparing this value, Pft, with the outputvalue Ptf from the pressure sensor 8 (Block 1011), if the differencebetween two values, Pfr−Pft, is a given value or larger, it is judgedthat the actual gaseous phase volume is smaller than the estimatedgaseous phase volume, that is, the fuel leakage may occur (Block 1012),then Block 1007 is selected next and consecutive control operations areperformed. In Block 1007, the fuel leakage locations are warned inassociation with the locations inside the fuel tank 3 or inside the fuelpipe 15, respectively.

[0044]FIG. 3 shows the relationship between the target feed pressurevalue and the output value from the fuel pressure sensor. As shown inFIG. 3, the output value from the fuel pressure sensor in relation tothe target feed pressure value varies for the cases including (a) whennormal operation (with nothing peculiar), (b) when vaporized fuels existin the pipe and (c) when fuel leakage occurs. In case of (a) normaloperation, that is, there is no abnormal state found in the fuel supplysystem, the target feed pressure value becomes almost identical to theactual fuel pressure sensed value, but in contrast, in case of (b)vaporized fuels existing, the actual fuel pressure value changes in thetime domain, and in case of (c) fuel leakage, the actual fuel pressurevalue does not exceed the target feed pressure value. By observing thisrelationship, it will be appreciated that the fuel state can be judgedaccurately, and that the influence by the fuel vaporization and the fuelleakage in the fuel pipe 15 can be reduced or removed.

[0045]FIG. 4 shows the relationship between the target feed pressurevalue and the output value from the fuel pressure when the enginestarts. When the key is turned on in order to start the engine 19, thefeed pump is operated and the fuel pressure rises up. According to thisfigure, it is proved that the transient characteristic in the rise-up ofthe fuel pressure changes dependent of the existence of the vaporizedareas in the fuel pipe 15.

[0046]FIG. 5 shows a control flow chart when the engine starts. If it isjudged that the vaporized area exists in the fuel pipe 15 by referringto the transient characteristic in the rise-up of the fuel pressureshown in FIG. 4 (Block 1014), the target feed pressure is increased(Block 1015). In case that the vaporized fuel exists yet afterincreasing the target feed pressure, the fuel pipe 15 is cooled byoperating the temperature adjusting device 12 (Block 1016).

[0047]FIGS. 6A, 6B and 6C show examples of the configuration of thecooling structure including the fuel pipe 15 and the temperatureadjusting device in the fuel supply apparatus. In the configurationshown in FIG. 6A, a radiator 24 is used as the temperature adjustingdevice, and the cooled water path is integrated with the fuel pipe 15.Though it is allowed to divert the radiator 24 used for the coolingwater in the engine 19, it is preferable that the cooling pipe for thefuel pipe 15 is provided so as to be independent of the cooling pipe forthe engine because the temperature of the cooling water for the engineordinarily increased up to 80° C. In the configuration shown in FIG. 6B,a cooler is provided as the temperature adjusting device 12, and thepipe 25 for the refrigeration medium cooled by the cooler and the fuelpipe 15 are integrated as a single structure. Owing to this structure,there is such an advantage as the temperature control of the fuel pipe15 can be established precisely. In the configuration shown in FIG. 6C,a cooler is provided as the temperature adjusting device 12, and the airis used as the refrigeration medium and is led between the heatinsulation material 16 and the fuel pipe 15. As the heat content of theair is smaller than that of the liquidized refrigeration medium and thusthe heat exchange at the heat pipe 15 and the temperature adjustingdevice 12 can be established efficiently, there is such an advantage asthis configuration can provide more precise and quick response ratherthan those of FIGS. 6A and 6B.

[0048] According to. the first embodiment of the present invention, itwill be appreciated that, in case of using the low boiling point fuel,the fuel vaporization and leakage in the fuel tank 3 and the fuel pipe15 can be detected precisely and their affect can be reduced or removed.In this embodiment, it is apparent from the above description that thefuel supply apparatus can be established even by the control only withthe feed pump 6 in the fuel tank 3 and without configured componentssuch as the temperature adjusting device 12, the radiator 24 and theheat insulation material 16, in which the control accuracy and itsapplication range may be sacrificed.

[0049]FIG. 7 illustrates the configuration of the fuel supplyingapparatus and its control flow diagram schematically in the secondembodiment of the present invention. The configuration of thisembodiment is characterized by that the pressure control device 9 isused in the fuel tank as the fuel conveying means instead of the feedpup shown in the first embodiment. This pressure control device 9maintains the internal pressure of the fuel tank 3 to be higher than theatmospheric pressure (preferably 5 kgf/cm2 or larger) as well as enablesto convey the fuel, which establishes a low cost system. The basicstructure except this feature is identical to the structure in the firstembodiment. The method for controlling the fuel state in this embodimentis described below by referring to FIGS. 8 to 11.

[0050]FIG. 8 shows an flow chart for controlling the fuel state in thesecond embodiment of the present invention in which the engine 19 (aninternal combustion engine in this embodiment) is in operation. In FIG.8, when the engine is in operation, the fuel 5 is fed with a designatedpressure (preferably 5 kgf/cm2 or larger) by using the pressure controldevice 9 (Block 1101). This feed pressure is selected from the targetfeed pressure values predefined in ECUL in responsive to the operationalcondition, the ambient air condition and the output value from the fueltemperature sensor 14. Next, the fuel pressure and temperature in thefuel pipe 15 are detected by the fuel pressure sensor 13 and the fueltemperature sensor 14, and the output values from the fuel remainingvolume sensor 7, the pressure sensor 8 the elastomatic film expansionsensor 10 are read in as the information on the state inside the fueltank 4 (Block 1102). At this step, by comparing the target pressurevalue of the pressure control device 9 with the output value from thefuel pressure sensor in the fuel pipe 15, the feed back control isperformed so that the output value from the pressure control device 9may become the target feed pressure value. Next, the fuel state isjudged (Block 1103), and then the target pressure value is increasedwhen the vaporized fuel exists (Block 1104). In case that there exists avaporized fuel yet after increasing the target pressure, the fuel pipe15 is made cooled by operating the temperature adjusting device 12(Block 1105). In case that the fuel leakage is detected in the result ofBlock 1103, the pressure of the pressure control device 9 is decreased(Block 1106), and in case that the engine 19 is loaded in the vehicle,the fixed power generator or the fixed compression refrigeratingmachine, the warning sound or light is issued to the user of the vehicle(Block 1107). In case that the fuel leakage volume is large or that thefuel leakage volume is a given value or larger even after decreasing thefeed pump pressure, the operation of the engine is terminated byshutting down the fuel supply by closing the electromagnetic valve 22after issuing the warning signal to the user (Block 1108). In case thatthe engine 19 is used in a vehicle and its system is configured like ahybrid automotive in which the drive system is driven by the motor aswell as the engine 19, it is allowed to operate the drive system withthe motor while the fuel supply to the engine 19 is suspended. As forthe fuel state in the fuel tank 3, comparing the output value Pft (theinstruction value Pft) by the pressure control device 9 with the outputvalue Pfr from the pressure sensor 8 (Block 1109), if the differencebetween two values, Pft−Pfr, is a given value or larger, it is judgedthat the actual gaseous phase volume is smaller than the estimatedgaseous phase volume, that ,s, the fuel leakage ma occur (Block 1112)and then Block 1107 is selected next and consecutive control operationsare performed. In Block 1007, the fuel leakage locations are warned inassociation with the locations inside the fuel tank 3 or inside the fuelpipe 15, respectively. In view of protecting the elastomatic film 4, therange of the pressure applied by the pressure control device 9 iscontrolled so that the output value of the expansion sensor may be belowa given value.

[0051]FIG. 9 shows the relationship between the target pressure valueand the output value from the fuel pressure sensor. As shown in FIG. 9,the output value from the fuel pressure sensor in relation to the targetpressure value varies for the cases including (a) when normal operation(with nothing peculiar), (b) when vaporized fuels exist in the pipe and(c) when fuel leakage occurs. In case of (a) normal operation, that is,there is no abnormal state found in the fuel supply system, the targetpressure value becomes almost identical to the actual fuel pressuresensed value, but in contrast, in case of (b) vaporized fuels existing,the actual fuel pressure value changes in the time domain, and in caseof (c) fuel leakage, the actual fuel pressure value does not exceed thetarget pressure value. By observing this relationship, it will beappreciated that the fuel state can be judged accurately, and that theinfluence by the fuel vaporization and the fuel leakage in the fuel pipe15 can be reduced or removed.

[0052]FIG. 10 shows the relationship between the target pressure valueand the output value from the fuel pressure when the engine starts. Whenthe key is turned on in order to start the engine 19, the feed pump isoperated and the fuel pressure rises up. According to this figure, it isproved that the transient characteristic in the rise-up of the fuelpressure changes dependent of the existence of the vaporized areas inthe fuel pipe 15.

[0053]FIG. 11 shows a control flow chart when the engine starts. If itis judged that the vaporized area exists in the fuel pipe 15 byreferring to the transient characteristic in the rise-up of the fuelpressure shown in FIG. 10 (Block 1114), the target pressure of thepressure control device 9 is increased (Block 1115). In case that thevaporized fuel exists yet after increasing the target pressure, the fuelpipe 15 is cooled by operating the temperature adjusting device 12(Block 1116).

[0054] According to the second embodiment of the present invention, itwill be appreciated that, in case of using the low boiling point fuel,the fuel vaporization and fuel leakage in the fuel tank 3 and the fuelpipe 15 can be detected precisely and their affect can be reduced orremoved. In this embodiment, the fuel supply apparatus can beestablished even by the control only with the feed pump 6 in the fueltank 3 and without configured components such as the temperatureadjusting device 12, the radiator 24 and the heat insulation material16, in which the control accuracy and its application range may besacrificed.

[0055] The apparatus with an internal combustion engine loaded includesa vehicle, a fixed electric generator and a fixed compressionrefrigerating machine.

[0056] It is also more effective by combining with structuralimprovement in the fuel tank and the fuel pipe in order to prevent thevaporization and leakage.

[0057] The embodiments in the present invention can be summarized asfollows.

[0058] (Embodiment 1)

[0059] In the claim 11 or 12, the fuel state control means control thevoltage of said fuel conveying means in responsive to the detectionresults of said fuel state detecting means and said fuel leakagedetecting means.

[0060] (Embodiment 2)

[0061] In the Embodiment 1, said fuel leakage protecting means isprovided inside said fuel storing means.

[0062] (Embodiment 3)

[0063] In the Embodiment 2, said fuel leakage protecting means is madewith an elastomatic material having an expandable mechanicalcharacteristic, and stores said low boiling point fuel inside theelastomatic container.

[0064] (Embodiment 4)

[0065] In the Embodiment 2 or 3, said fuel leakage protecting means ismade with an elastomatic material having an expandable mechanicalcharacteristic, and changes the volume inside said elastomatic containerin responsive to the detection results of said fuel state detectingmeans and said fuel leakage detecting means.

[0066] (Embodiment 5)

[0067] In the Embodiment 1 to 4, said fuel state controlling means isprovided outside said fuel pipe.

[0068] (Embodiment 6)

[0069] In the Embodiment 5, said fuel state controlling means is atemperature adjusting device attached to said fuel pipe.

[0070] (Embodiment 7)

[0071] In the Embodiment 6, said fuel state controlling means is arefrigeration medium passing through said fuel pipe.

[0072] (Embodiment 8)

[0073] In the Embodiment 7, the temperature of said refrigeration mediumis controlled by said temperature adjusting device.

[0074] (Embodiment 9)

[0075] In the Embodiment 7 or 8, said refrigeration medium is water andpasses in the radiator for the cooling water of said internal combustionengine through said pipe attached to said fuel pipe.

[0076] (Embodiment 10)

[0077] In the Embodiments 1 to 9, said fuel leakage detecting means ispreferably composed of at least one of a fuel pressure sensor providedin said fuel pipe, a pressure sensor provided in said fuel storingmeans, a fuel temperature sensor provided at said fuel pipe or said fuelstoring means, a fuel remaining sensor for detecting the remainingvolume of said low boiling point fuel in the said storing means, avolume detecting sensor for detecting the volume of the elasticatedcontainer provided in said fuel storing means and said fuel conveyingmeans; and estimates the fuel leakage amount according to the outputsignals from the individual sensors and means and their calculationresult.

[0078] (Embodiment 11)

[0079] In the Embodiments 1 to 10, said fuel leakage detecting means ispreferably composed of at leas one of a fuel pressure sensor provided insaid fuel pipe, a pressure sensor provided in said fuel storing means, afuel temperature sensor provided at said fuel pipe or said fuel storingmeans, a fuel remaining sensor for detecting the remaining volume ofsaid low boiling point fuel in said fuel storing means, a volumedetecting sensor for detecting the volume of the elasticated containerprovided in said fuel storing means and said fuel conveying means, andestimates the fuel leakage location according to the output signals fromthe individual sensors and means and their calculation result.

[0080] (Embodiment 12)

[0081] In the Embodiment 11, in case that the estimated value of thefuel leakage volume is a given value or larger, the operation of saidinternal combustion engine is terminated.

[0082] (Embodiment 13)

[0083] In the Embodiment 11, a fuel leakage warning means is providedfor signaling at least one of the alarm sound or the alarm lamp to theuser of the apparatus with said internal combustion engine loaded incase that the estimated value for the fuel leakage amount is adesignated value or larger.

[0084] (Embodiment 14)

[0085] In the Embodiments 1 to 11, a fuel supply apparatus described inthe claim 14 having a fuel leakage location alarming means is provided.

[0086] (Embodiment 15)

[0087] In the claim 2, in case that at least one means of the fuelstoring means for storing said low boiling point fuel; the fuelconveying means for conveying said low boiling point fuel from said fuelstoring means to the engine; the fuel pipe for leading said low boilingpoint fuel to be conveyed from said fuel storing means to said internalcombustion engine; the fuel leakage protecting means for preventing theleakage of said low boiling point fuel in said fuel storing means or insaid fuel pipe; the fuel leakage detecting means for detecting theleakage of said low boiling point fuel in said fuel storing means or insaid fuel pipe; the fuel state detecting means for detecting the fuelstate in said fuel storing means or in said fuel pipe; and the fuelstate controlling means for controlling the fuel state in said fuelstoring means or in said fuel pipe is defected, the operation of saidinternal combustion engine is terminated.

[0088] (Embodiment 16)

[0089] In the claim 2, in case that at least one means of the fuelstoring means for storing said low boiling point fuel; the fuelconveying means for conveying said low boiling point fuel from said fuelstoring means to the engine; the fuel pipe for leading said low boilingpoint fuel to be conveyed from said fuel storing means to said internalcombustion engine; the fuel leakage protecting means for preventing theleakage of said low boiling point fuel in said fuel storing means or insaid fuel pipe; the fuel leakage detecting means for detecting theleakage of said low boiling point fuel in said fuel storing means or insaid fuel pipe; the fuel state detecting means for detecting the fuelstate in said fuel storing means or in said fuel pipe; and the fuelstate controlling means for controlling the fuel state in said fuelstoring means or in said fuel pipe is defected, the fuel leakagealarming means is provided for signaling at least one of the alarm soundor the alarm lamp to the user of the apparatus with said internalcombustion engine loaded.

[0090] (Embodiment 17)

[0091] In the claim 2, in case that at least one means of the fuelstoring means for storing said low boiling point fuel; the fuelconveying means for conveying said low boiling point fuel from said fuelstoring means to the engine; the fuel pipe for leading said low boilingpoint fuel to be conveyed from said fuel storing means to said internalcombustion engine; the fuel leakage protecting means for preventing theleakage of said low boiling point fuel in said fuel storing means or insaid fuel pipe; the fuel leakage detecting means for detecting theleakage of said low boiling point fuel in said fuel storing means or insaid fuel pipe; the fuel state detecting means for detecting the fuelstate in said fuel storing means or in said fuel pipe; and the fuelstate controlling means for controlling the fuel state in said fuelstoring means or in said fuel pipe is defected, the fuel system faultlocation alarming means is provided for estimating which means is faultand reporting its estimation result to the user of the apparatus withsaid internal combustion engine loaded.

[0092] According to the above described embodiments, the followingstructures can be provided.

[0093] A fuel supply apparatus using a low boiling point fuel,comprising

[0094] a control apparatus generating an electric signal in responsiveto at least either of the fuel leakage volume or the fuel vaporizationstate; and

[0095] a adjusting apparatus for adjusting at least either of the fuelpressure or the fuel temperature in responsive to the output signal fromsaid control apparatus.

[0096] A fuel supply apparatus using a low boiling point fuel,comprising

[0097] a first fuel pressure sensor detecting the fuel pressure in thefuel storing container;

[0098] a second fuel pressure sensor detecting the fuel pressure in thefuel pipe leading the fuel from said fuel storing container to theengine; and

[0099] a fuel flow rate adjusting apparatus for adjusting at least oneof said fuel pressure or fuel temperature when the output signals fromboth pressure sensors reaches a specified condition.

[0100] A fuel supply apparatus using a low boiling point fuel,comprising

[0101] a pressure sensor detecting the fuel pressure in the fuel pipeleading the fuel from said fuel storing container to the engine;

[0102] a temperature sensor detecting the fuel temperature in the fuelpipe leading the fuel from said fuel storing container to the engine;and

[0103] a fuel flow rate adjusting apparatus for adjusting the fuel flowrate in said fuel pipe when the output signals from both sensors reachesa specified condition.

[0104] A method for controlling a fuel supply apparatus for supplying alow boiling point fuel having a vapor phase at the normal temperaturesand the atmospheric pressures, wherein

[0105] said fuel supply apparatus comprises

[0106] a fuel storing means for storing the low boiling point fuel;

[0107] a fuel conveying means for conveying the low boiling point fuelfrom the fuel storing means;

[0108] a fuel pipe for leading the low boiling point fuel to be conveyedfrom the fuel storing means;

[0109] a fuel leakage protecting means for preventing the leakage of thelow boiling point fuel in the fuel storing means or in the fuel pipe;

[0110] a fuel leakage detecting means for detecting the fuel leakage inthe fuel storing means or in the fuel pipe;

[0111] a fuel state detecting means for detecting the fuel state in thefuel storing means or in the fuel pipe; and

[0112] a fuel state controlling means for controlling the fuel state inthe fuel storing means or in the fuel pipe, in which at least one of thestates in the fuel storing means, the fuel conveying means, and

[0113] at least one state of the fuel storing means, the fuel conveyingmeans, the fuel pipe and the fuel leakage protecting is controlled byusing the fuel state controlling means in responsive to the detectionresult by the fuel state detecting means and the fuel leakage detectingmeans.

[0114] More specifically and preferably, in the above described fuelsupply apparatus, the fuel state controlling means controls at least oneof the temperature, the pressure and the shape in the fuel storingmeans, the fuel pipe and the fuel leakage protecting means in responsiveto the detection result by the fuel state detecting means and the fuelleakage detecting means.

[0115] The fuel supply apparatus of the present invention enables toreduce the fuel evaporation and the fuel leakage by controlling the fuelstate in responsive to the fuel vaporization and fuel leakage state inthe fuel storing container and in the fuel pipe in case of using a lowboiling point fuel having a vapor phase in the normal temperatures andatmospheric pressures.

What is claimed is:
 1. A fuel supply apparatus using a low boiling pointfuel comprising a fuel storing container; and another container made ofelastomatic material having an expandable mechanical characteristicinside said fuel storing container.
 2. A fuel supply apparatus using alow boiling point fuel of claim 1, wherein a feed pump is providedinside said another container made of elastomatic material.
 3. A fuelsupply apparatus using a low boiling point fuel comprising a fuel pipeleading a low boiling point fuel stored in a fuel storing container; anda temperature adjusting device for heating or cooling said fuel pipe. 4.A fuel supply apparatus using a low boiling point fuel of claim 3,wherein said fuel pipe is covered by an insulation material.
 5. A fuelsupply apparatus using a low boiling point fuel of claim 3, wherein saidfuel pipe and a flow route member for flowing a refrigeration medium forheating or cooling said fuel pipe are placed so as to be close to eachother, and both are covered by an insulation material.
 6. A fuel supplyapparatus using a low boiling point fuel comprising a fuel pipe forleading a low boiling point fuel stored in a fuel storing container toan engine; and a flow rate controlling apparatus for adjusting the flowrate of the fuel in the fuel pipe.